Position and singularity analysis of a class of planar parallel manipulators with a reconfigurable end-effector

Parallel robots with configurable platforms are a class of robots in which the end-effector has an inner mobility, so that its overall shape can be reconfigured: in most cases, the end-effector is thus a closed-loop kinematic chain composed of rigid links. These robots have a greater flexibility in their motion and control with respect to rigid-platform parallel architectures, but their kinematics is more challenging to analyze. In our work, we consider n-RRR planar configurable robots, in which the end-effector is a chain composed of n links and revolute joints, and is controlled by n rotary actuators located on the base of the mechanism. In particular, we study the geometrical design of such robots and their direct and inverse kinematics for n = 4, n = 5 and n = 6; we employ the bilateration method, which can simplify the kinematic analysis and allows us to generalize the approach and the results obtained for the 3-RRR mechanism to n-RRR robots (with n > 3). Then, we study the singularity configurations of these robot architectures. Finally, we present the results from experimental tests that have been performed on a 5–RRR robot prototype

On the feasibility of utilising gearing to extend the rotational workspace of a class of parallel robots

Parallel manipulators provide several benefits compared to serial manipulators of similar size. These advantages typically include higher speed and acceleration, improved position accuracy and increased stiffness. However, parallel manipulators also suffer from several disadvantages. These drawbacks commonly include a small ratio of the positional workspace relative to the manipulator footprint and a limited rotational capability of the manipulated platform. A few parallel manipulators featuring a large ratio of the positional workspace relative to the footprint have been proposed. This paper investigates the feasibility of employing gearing to extend the range of the end-effector rotation of such mechanisms. The objective is to achieve parallel manipulators where both the positional and rotational workspace are comparable to that of serial manipulators

Performance Comparison of Several Control Algorithms for Tracking Control of Pantograph Mechanism

A sort of parallel manipulator known as a pantograph robot mechanism was created primarily for industrial requests that required high precision and satisfied speed. While tracking a chosen trajectory profile requires a powerful controller. Because it has four active robot links and one robot passive link in place of just two links like the open chain does, it can carry more loads than the open chain robot mechanism while maintaining accuracy and stability. The calculated model for a closed chain pantograph robot mechanism presented in this paper takes into account the boundary conditions. For the purpose of simulating the dynamics of the pantograph robot mechanism, an entire MATLAB Simulink has been created. The related Simscape model had been created to verify the pantograph mathematical model that had been provided. Five alternative tracking controllers were also created and improved using the Flower Pollination (FP) algorithm. The PID controller, which is used in many engineering applications, is the first control. An enriched Fractional Order PID (FOPID) controller is the second control. The third control considers an improved Nonlinear conventional PID (NLPID) controller, and the parameters for this controller were likewise determined using (FP) optimization using the useful objective function. Model Reference Adaptive Control (MRAC) with PID Compensator is the fourth control. The Fuzzy PD+I Control is the last and final controller. A comparison of the different control methods was completed. A rectangular trajectory was chosen as the end effector of the pantograph robot\u27s position reference because it displays performance during sharp edges and provides a more accurate study. The proposed controllers were used for this task to analyse the performance. The outcomes demonstrate that the Fuzzy PD+I control outperforms the PID, FOPID, NLPID, and MRAC with PID Compensator controllers in terms of performance. In the case of the Fuzzy PD+I control, the angles end effector has a lower rise time, a satisfied settling time, and low overshoot with good precision

Cooperative Control of the Dual Gantry-Tau Robot

Utilization of multiple parallel robots operating in the same work place and cooperating on the same job have opened up new challenges in coordination control strategies. Multiple robot control is a natural progression for Parallel Kinematic Machines (PKM) as it offers many of the desirable qualities especially in cooperative arrangements where multiple robots can be associated with an easily reconfigurable parallel machine. These special characteristics allow much faster and precise manipulations especially in manufacturing industries. With the possibility of cooperative control architecture, PKMs will be able to perform many of the tasks currently requiring dual serial robots such as complex assemblies, heavy load sharing and large machining jobs

Dynamic visual servoing from sequential regions of interest acquisition.: On behalf of: Multimedia Archives Dynamic visual servoing from sequential regions of interest acquisition.

International audienceOne of the main drawbacks of vision-based control that remains unsolved is the poor dynamic performances caused by the low acquisition frequency of the vision systems and the time latency due to processing. We propose in this paper to face the challenge of designing a high-performance dynamic visual servo control scheme. Two versatile control laws are developed in this paper: a position-based dynamic visual servoing and an image-based dynamic visual servoing. Both control laws are designed to compute the control torques exclusively from a sequential acquisition of regions of interest containing the visual features to achieve an accurate trajectory tracking. The presented experiments on vision-based dynamic control of a high-speed parallel robot show that the proposed control schemes can perform better than joint-based computed torque control

Robot Manipulators

Robot manipulators are developing more in the direction of industrial robots than of human workers. Recently, the applications of robot manipulators are spreading their focus, for example Da Vinci as a medical robot, ASIMO as a humanoid robot and so on. There are many research topics within the field of robot manipulators, e.g. motion planning, cooperation with a human, and fusion with external sensors like vision, haptic and force, etc. Moreover, these include both technical problems in the industry and theoretical problems in the academic fields. This book is a collection of papers presenting the latest research issues from around the world

Kinematics and Robot Design I, KaRD2018

This volume collects the papers published on the Special Issue “Kinematics and Robot Design I, KaRD2018” (https://www.mdpi.com/journal/robotics/special_issues/KARD), which is the first issue of the KaRD Special Issue series, hosted by the open access journal “MDPI Robotics”. The KaRD series aims at creating an open environment where researchers can present their works and discuss all the topics focused on the many aspects that involve kinematics in the design of robotic/automatic systems. Kinematics is so intimately related to the design of robotic/automatic systems that the admitted topics of the KaRD series practically cover all the subjects normally present in well-established international conferences on “mechanisms and robotics”. KaRD2018 received 22 papers and, after the peer-review process, accepted only 14 papers. The accepted papers cover some theoretical and many design/applicative aspects

Contributions à la maîtrise de la dynamique des robots parallèles

Ce mémoire traite de mes contributions à la maîtrise de la dynamique des robots parallèles. Le premier chapitre présente une introduction générale de mes travaux de recherche. Le deuxième chapitre présente mon curriculum vitae. Mes activités d'encadrement, les projets de recherche que j'ai montés ainsi que ceux auxquels j'ai participé et une synthèse de mes collaborations nationales et internationales sont mentionnés dans le troisième chapitre. Mon rayonnement au sein de la communauté scientifique, qui se traduit par des activités d'intérêt général, la participation à des comités d'expertise, des activités éditoriales, la participation à l'organisation de colloques et quelques distinctions scientifiques, ainsi que la liste de mes publications ont été décrits dans le quatrième chapitre. Le cinquième chapitre synthétise mes activités d'enseignement. Le sixième chapitre présente plus en détail mes activités de recherche principales qui sont organisées autour des deux thèmes suivants : (i) Maîtrise de la dynamique des robots parallèles ; (ii) Conception et commande de nouveaux robots parallèles aux performances dynamiques améliorées. Enfin, le septième chapitre présente mes conclusions sur les travaux que j’ai pu mener ainsi que mes perspectives de recherche.Les activités de recherche que j'ai menées portent principalement sur la maîtrise de la dynamique des robots parallèles qui sont des architectures mécaniques complexes dont les performances dynamiques sont encore mal maîtrisées. J'ai cherché à mieux maîtriser la dynamique de ces machines à deux niveaux :1.un premier niveau intitulé « maîtrise de la dynamique des robots parallèles » qui se situe en aval de la phase de réalisation du robot : pour une machine donnée, comment mieux maîtriser ses performances dynamiques (par une modélisation plus fine, par la compréhension des phénomènes physiques mis en jeu et leur gestion par planification de trajectoire ou mise en place de contrôleurs avancés, etc.) ?2.un second niveau intitulé « conception et commande de nouveaux robots parallèles aux performances statiques et dynamiques améliorées» qui se situe en amont de la phase de réalisation du robot : pour des performances statiques et/ou dynamiques à atteindre, comment concevoir l'architecture de robot, voire la bonne adéquation {architecture de robot – contrôleur} qui permet de répondre au cahier des charges désiré ?Ces deux approches ne sont pas antagonistes, mais au contraire, elles sont complémentaires.Mes contributions principales autour de la maîtrise de la dynamique des robots parallèles se sont concentrées sur quatre points majeurs :1.L'étude des conditions de dégénérescence du modèle dynamique des robots parallèles 2.L'identification des paramètres du modèle dynamique rigide 3.La modélisation élastodynamique4.La proposition de techniques d'équilibrage permettant de diminuer la complexité de mise en oeuvreMes contributions principales autour de la conception et commande de nouveaux robots parallèles aux performances statiques et dynamiques améliorées se sont concentrées sur deux travaux majeurs :1.La conception de robots pour le déplacement de lourdes charges2.La conception et la commande de robots rapides et précisTous les résultats présentés, exception faite de ceux sur l'équilibrage dynamique, ont été validés expérimentalement.Les travaux présentés en perspectives se concentrent autour de deux grands axes thématiques:1.Maîtrise de la dynamique des systèmes,2.Conception de robots orientée environnements.Les activités que je souhaite mener sur la maîtrise de la dynamique des systèmes ciblent :a)La reconfiguration dynamique des robots,b)La modélisation et l'identification basées perception.Ces activités, qui s'inscrivent dans la continuité de mes travaux de recherche actuels.L'objectif du thème « Conception de robots orientée environnements », qui est un thème en rupture, est de proposer des méthodes génériques pour l'analyse, l'évaluation et la conception de nouvelles architectures de robots et de mécanismes,•en fonction d'un environnement donné (environnement en termes de milieu dans lequel le robot évolue, interagit, etc.) : le robot doit être doté d'un système de perception efficace associé à un contrôleur performant et il faut penser la conception du robot de manière intégrée afin que l'ensemble {architecture mécanique – contrôleur – capteurs –moteurs} soit le plus performant possible.•à faible impact pour l'environnement dans lequel ils évoluent (moins de pollution, moins de consommation énergétique, etc.)Les activités que je souhaite mener en conception orientée environnements ciblent :a)La proposition de méthodologies de conception orientée commande qui vont permettre de faire en sorte que l'ensemble {architecture mécanique – contrôleur – capteurs – moteurs} soit le plus performant possible pour une tâche, un ensemble de tâches, ou un environnement donnés,b)La conception de robots à faibles impacts environnementaux

Modeling and Control of the Cooperative Automated Fiber Placement System

The Automated Fiber Placement (AFP) machines have brought significant improvement on composite manufacturing. However, the current AFP machines are designed for the manufacture of simple structures like shallow shells or tubes, and not capable of handling some applications with more complex shapes. A cooperative AFP system is proposed to manufacture more complex composite components which pose high demand for trajectory planning than those by the current APF system. The system consists of a 6 degree-of-freedom (DOF) serial robot holding the fiber placement head, a 6-DOF revolute-spherical-spherical (RSS) parallel robot on which a 1-DOF mandrel holder is installed and an eye-to-hand photogrammetry sensor, i.e. C-track, to detect the poses of both end-effectors of parallel robot and serial robot. Kinematic models of the parallel robot and the serial robot are built. The analysis of constraints and singularities is conducted for the cooperative AFP system. The definitions of the tool frames for the serial robot and the parallel robot are illustrated. Some kinematic parameters of the parallel robot are calibrated using the photogrammetry sensor. Although, the cooperative AFP system increases the flexibility of composite manufacturing by adding more DOF, there might not be a feasible path for laying up the fiber in some cases due to the requirement of free from collisions and singularities. To meet the challenge, an innovative semi-offline trajectory synchronized algorithm is proposed to incorporate the on-line robot control in following the paths generated off-line especially when the generated paths are infeasible for the current multiple robots to realize. By adding correction to the path of the robots at the points where the collision and singularity occur, the fiber can be laid up continuously without interruption. The correction is calculated based on the pose tracking data of the parallel robot detected by the photogrammetry sensor on-line. Due to the flexibility of the 6-DOF parallel robot, the optimized offsets with varying movements are generated based on the different singularities and constraints. Experimental results demonstrate the successful avoidance of singularities and joint limits, and the designed cooperative AFP system can fulfill the movement needed for manufacturing a composite structure with Y-shape

Redundant Hybrid Cable-Driven Robots: Modeling, Control, and Analysis

Serial and Cable-Driven Parallel Robots (CDPRs) are two types of robots that are widely used in industrial applications. Usually, the former offers high position accuracy at the cost of high motion inertia and small workspace envelope. The latter has a large workspace, low motion inertia, and high motion accelerations, but low accuracy. In this thesis, redundant Hybrid Cable-Driven Robots (HCDRs) are proposed to harness the strengths and benefits of serial and CDPRs. Although the study has been directed at warehousing applications, the developed techniques are general and can be applied to other applications. The main goal of this research is to develop integrated control systems to reduce vibrations and improve the position accuracy of HCDRs. For the proposed HCDRs, the research includes system modeling, redundancy resolution, optimization problem formulation, integrated control system development, and simulation and experimental validation. In this thesis, first, a generalized HCDR is proposed for the step-by-step derivation of a generic model, and it can be easily extended to any HCDRs. Then, based on an in-plane configuration, three types of control architecture are proposed to reduce vibrations and improve the position accuracy of HCDR. Their performance is evaluated using several well-designed case studies. Furthermore, a stiffness optimization algorithm is developed to overcome the limitations of existing approaches. Decoupled system modeling is studied to reduce the complexity of HCDRs. Control design, simulations, and experiments are developed to validate the models and control strategies. Additionally, state estimation algorithms are proposed to overcome the inaccurate limitation of Inertial Measurement Unit (IMU). Based on these state observers, experiments are conducted in different cases to evaluate the control performance. An Underactuated Mobile Manipulator (UMM) is proposed to address the tracking and vibration- and balance-control problems. Out-of-plane system modeling, disturbance analysis, and model validation are also investigated. Besides, a simple but effective strategy is developed to solve the equilibrium point and balancing problem. Based on the dynamic model, two control architectures are proposed. Compared to other Model Predictive Control (MPC)-based control strategies, the proposed controllers require less effort to implement in practice. Simulations and experiments are also conducted to evaluate the model and control performance. Finally, redundancy resolution and disturbance rejection via torque optimization in HCDRs are proposed: joint-space Torque Optimization for Actuated Joints (TOAJ) and joint-space Torque Optimization for Actuated and Unactuated Joints (TOAUJ). Compared to TOAJ, TOAUJ can solve the redundancy resolution problem as well as disturbance rejection. The algorithms are evaluated using a Three-Dimensional (3D) coupled HCDR and can also be extended to other HCDRs